Surgical irrigation apparatus and method of using same

ABSTRACT

Apparatus for delivering large quantities of sterile medical liquid at both a fast flow rate and a low pressure to a resectoscope used by a physician in performing prostate surgery. Each of several 2-liter bottles suspended above the patient has an outlet tube providing for simultaneous concurrent flow of liquid and air between the bottle and an air trap chamber of the apparatus. In the process of maintaining a constant supply of bubble-free liquid to the resectoscope for flushing out blood and tissue, any randomly selected bottle of the apparatus that becomes empty can be disconnected from its outlet tube and replaced with a full bottle without disrupting the liquid supply to the air trap chamber from any other bottle of the apparatus.

United States Patent McPhee 51 July 18, 1972 SURGICAL IRRIGATIONAPPARATUS AND METHOD OF USING SAME [72] Inventor: Charles J. McPhee,Sylmar, Calif. [73] Assignee: American Hospital Supply Corporation [22]Filed: Aug. 27, 1970 21 Appl. No.: 67,375

[52] US. Cl ..128/227,137/l27, 141/319, 222/416 [51] Int. Cl. ..A6lm3/00 [58] Field of Search 128/227, 228, 213, 214, 272, 128/275, DIG. 12,DIG. l3; 137/123-127, 602-607; 222/129, 145, 416; 141/311, 319-323, 285[56] References Cited UNITED STATES PATENTS 3,217,711 11/1965 Pecina etal. ..l28/2l4 3,110,308 11/1963 Bellamy,-Jr. 128/272 X 2,775,240 12/1956Morrisey, Jr. et al... ....128/214 2,542,461 2/1951 Bay ....128/2282,027,588 1/1936 Hannon..... ....l28/227 2,954,028 9/1960 Smith..l28/214 2,594,639 4/1952 Gossett ...l28/2l4 X 3,216,418 11/1965Scislowicz ..l28/214 FOREIGN PATENT OR APPLICATIONS 737,249 6/1966Canada ..128/2l4 OTHER PUBLICATIONS Intravenous Transfusion Set forInfants" The Lancet, April 27, 1963, p. 923- 924 Primary ExaminerRichardA. Gaudet Assistant Examiner-J. Yasko Att0rneyLarry N. Barger and RobertT. Merrick [57] ABSTRACT Apparatus for delivering large quantities ofsterile medical liquid at both a fast flow rate and a low pressure to aresectoscope used by a physician in performing prostate surgery. Each ofseveral 2-1iter bottles suspended above the patient has an outlet tubeproviding for simultaneous concurrent flow of liquid and air between thebottle and an air trap chamber of the apparatus. In the process ofmaintaining a constant supply of bubble-free liquid to the resectoscopefor flushing out blood and tissue, any randomly selected bottle of theapparatus that becomes empty can be disconnected from its outlet tubeand replaced with a full bottle without disrupting the liquid supply tothe air trap chamber from any other bottle of the apparatus.

19 Claims, 6 Drawing Figures Patented July 18, 1972 4 Sheets-Sheet 2 hasJ 449 /9 66 INVE1\T0R g /fii 5 C'HA ' Patented July 18, 1972 4Sheets-Sheet Z 671146465 J M PHCC'E ATTOE/Vmfy Patented July 18, 19723,677,248

' 4 Sheets-Sheet 4 SURGICAL IRRIGATION APPARATUS AND METHOD OF USINGSAME BACKGROUND A very common surgical operation performed in males asthey grow older is a Transurethral Resection (T.U.R.) commonly known asa prostate operation. In performing a prostate surgery, the physicianuses a resectoscope which he inserts into the patients urethral canal toview the prostate gland, which is shaped somewhat like a doughnut andlocated at the base of the bladder. As the physician cuts away portionsof the prostate gland to provide a free passage for urine through thegland to the urethra, there is considerable blood and tissue that canobstruct the physicians view through the resectoscope. During thesurgery, this blood and tissue are flushed out through the urethra witha stream of water or other liquid.

In the past there have been many problems in supplying the flushingliquid to the resectoscope. Because the liquid must be sterile to avoidpossible contamination and infection of the patient, tap water which isavailable in large quantities is not ordinarily used. Instead, sealedcontainers of sterile liquid are suspended above the patient to feed thesterile liquid through a tube to the resectoscope. Since such largevolumes of sterile liquid are needed often in excess of liters a singlecontainer with enough sterile liquid for a complete prostate surgerywould be too heavy and cumbersome for a nurse to handle and lift to ahanger above the patient. Therefore, smaller containers of l or 2 litersize for example have been used, and these were continually changed asthey became empty. Sometimes, when the bottles were changed, the liquidflow rate would change considerably causing a surging of the flushingliquid and making it harder for the physician to see the surgical site.Also, when changing containers, there was a problem of getting airbubbles or large slugs of air in the line leading to the resectoscopeand such air would give the physician an obstructive view. This wasbecause the air would not flush away the blood and tissue.

Another problem with prior systems for delivering liquid to aresectoscope was the pressure used to deliver such large volumes ofliquid at fast flow rates. To increase the flow rates the liquidcontainers were hung very high above the patient to increase the headpressure of the liquid and hence its flow rate. Sometimes a nurse evenhad to use a step stool or overhead winch to hang and change the sterileliquid containers. To get the fast flow rates necessary for goodflushing action during surgery, it was believed that high pressures wereneeded, even though high pressure delivery of flushing liquid was knownto' cause problems. To begin with, high pressure delivery could causeexcessive turbulence or splattering of the liquid, decreasing itsoptical clarity. Also, the flushing liquid under high pressure couldbuild up excessive static pressure in the patients bladder during andafter the bladder became filled with the flushing liquid. Finally, itwas a laborious task for a nurse to run up and down a step stool,lugging a 2-liter bottle of liquid every time a bottle suspended from ahigh perch became empty.

As mentioned above, surgical irrigation of a prostrate operation hasseveral unique problems including supplying high liquid volumes,maintaining fast flow rates; and the trouble with high pressure, airslugs, frequent bottle changes, etc. Because of these special problems,surgical irrigation is considered in a separate category from othermedical administration procedures such as oxygen administration of gasto a patient's lungs, or intravenous administration of blood orparenteral liquid at a slow drip-drip-drip rate into a patients vein.The applicants invention here deals with surgical irrigation and withovercoming the problems of previous surgical irrigation systems.

SUMMARY OF THE INVENTION of a prostate surgery. The apparatus hasseveral large glass or plastic bottles, 2-liter for example, containingsterile liquid suspended above the patient, and each bottle has anoutlet tube connected to a mouth of the bottle. These outlet tubes havelower ends leading to an enlarged air trap chamber which separatesliquid and air and drains the liquid through a tube to a resectoscope.Each outlet tube has a passage sufficiently large for simultaneousconcurrent flow of liquid and air providing each bottle with its ownindependently operating liquid-air interchange system with the air trapchamber. Thus, any randomly selected bottle of the apparatus thatbecomes empty can be disconnected from its outlet tube and replaced witha full bottle without disrupting the fast, steady liquid supply to theair trap chamber from other bottles of the apparatus. As long as atleast one bottle of the apparatus has some liquid in it, the apparatuswill continue to deliver bubblefree liquid to the resectoscope at aconstant low pressure. This constant low pressure delivery is broughtabout by a hydrophobic air inlet check valve at a mouth of each supplybottle that establishes a generally constant hydrostatic headindependant of the liquid level in the bottle. While liquid is flowinginto the air trap chamber from the supply bottles, any air collected inthe air trap chamber can work its way back up the outlet tubes to thesupply bottles. In one version of the invention the air can also exit tothe atmosphere through a unique check valve at a top of the air trapchamber.

THE DRAWINGS FIG. 1 is a front elevational view of the apparatusassembled for supplying low pressure bubble-free liquid at a fast flowrate to a resectoscope from glass bottles;

FIG. 2 is an enlarged sectional view of an outlet tube between one ofthe bottles and the air trap chamber showing the independently operatingliquid-air interchange system;

FIG. 3 is an enlarged sectional view of the top portion of the air trapchamber showing a modification of the air trap chamber with a specialcheck valve to assist in removing air from the air trap chamber; 1 I

FIG. 4 is a top plan view of the check valve taken along line 44 of FIG.3;

FIG. 5 is a front elevational view showing the apparatus with semirigidthermoplastic bottles with walls that flex inwardly in response to apartial vacuum created when liquid begins to drain, and these wallsthereafter move outwardly to suck back air to replace the drainedliquid; and

FIG. 6 is a front view of the apparatus as supplied to the hospital forconnecting to the bottles of sterile liquid and to the resectoscope, theair trap chamber of the apparatus being shown in perspective view.

DETAILED DESCRIPTION Referring specifically to these drawings, FIG. 1shows the apparatus as it is used with four 2-liter glass bottles. Thesebottles numbered 1, 2, 3, and 4 are hung above the patient by hangingbails 5, 6, 7 and 8, and these bottles have mouths 9, l0, l1 and 12 thatform the lowest points of the bottles when hung in an inverted positionas shown in FIG. 1. Bottles 1 and 2 are shown in solid lines dispensingliquid, with bottle 2 being the fuller of the two. Bottles 3 and 4 areshown in dotted line to show that these bottles became empty and werelowered to the position shown in full solid line for exchanging theempty bottles for two full bottles 3a and 4a. When the two full bottles3a and 4a are substituted for empty bottles 3 and 4, the full bottleswill be hung in the position of the dotted lines formerly occupied bybottles 3 and 4.

As can be seen from FIG. I, each bottle has an outlet tube, heredesignated as 13, 14, 15 and 16, and these tubes are connected at theirupper ends to closures l7, l8, l9 and 20, fitted to the bottle mouthsand at their lower ends 21, 22, 23 and 24 to an inlet structure of anenlarged air trap chamber 25. This inlet structure can be a cap 30 withfour separate ports that connect to the outlet tubes. Each outlet tubehas an on-off clamp designated as 26, 27, 28 and 29, and in thedrawings, these outlet tube clamps are shown in the open position. Whilethe empty bottles 3 and 4 are being exchanged for full bottles as inFIG. 1, clamps 28 and 29 are closed. The bottles 1 and 2 keep a faststeady supply of liquid flowing to the air trap chamber 25. At thispoint, it is important to recognize that each bottle has its own outlettube for delivering liquid to the air trap chamber, and the change overof the empty bottles 3 and 4 for full bottles does not interrupt thesupply of liquid from bottles 1 and 2. Each outlet tube has its ownindependently operating liquid-air'exchange system with the air trapchamber 25. Thus, any air introduced into the air trap chamber can workits way back up into the bottles to replace liquid flowing to the airtrap chamber. The details of these liquid-air interchange systems willbe discussed in more detail with, reference to subsequent drawings afterwe explore the entire apparatus of FIG. 1.

After the liquid collects in the enlarged air trap chamber of FIG. 1,any air bubbles entrained in the liquid gushing through the inletstructure of the top cap of the air trap chamber moves to the top of thechamber and creates a liquidair interface 31 which is readily visiblethrough transparent cylindrical chamber wall 32. Wall 32 can havevolumetric calibrations, if desired, to give the physician or nurse areading of how full the air trap chamber is running. The liquid in thelower portion of the air trap chamber drains out through a drain port 33in a bottom cap 34 secured to the chamber wall. A flexible thermoplasticdrain tube 35 connected at its upper end to the drain port 33 carriesliquid from the air trap chamber to the drain tubes lower end which isconnected to rigid adapter 36. Fitting around this adapter is anelastomeric sleeve 37 that is adapted to stretch over a hollow knobconnector on a resectoscope to join the drain tube 35 with theresectoscope.

In FIG. 1, the lower end of drain tube 35, adapter 36 and elastomericsleeve 37 are shown covered by a removable sterility protector whichincludes a retainer with a disc member 38 and a skirt 39 fitting aroundthe drain tube. Removably fitting within the skirt is one end of atransparent protector housing 40 which is closed at outer end 41. Theprotector housing 40 is pulled away from the skirt 39 of the retainerimmediately before the physician connects elastomeric sleeve 37 to theresectoscope. The purpose of the protector housing is to keep theelastomeric sleeve sterile until connected to the resectoscope. Theresectoscope itself is old in the art and not part of this invention.Hence, the intricate details of the resectoscope are not shown in thedrawings.

Now that we have discussed the overall surgical irrigation apparatus ofFIG. 1, we move on to the more specific details of the internalstructure of this apparatus shown in subsequent figures. As explainedbriefly above, each bottle has its own independently operatingliquid-air interchange system with the air trap chamber. Thus, anyrandomly selected bottle that becomes empty can be taken down andexchanged with a full bottle without disturbing the liquid supply to theair trap chamber from any other bottle of the apparatus. FIG. 2 perhapsbest shows how this liquid-interchange system works. As shown in thedrawing, each outlet tube has a passage between its ends which issufficiently large in diameter for simultaneous concurrent flow ofliquid and air. I have found that a tube with a passage between 0.150inch and 0.400 inch diameter works very well for this purpose. A tubewith a passage substantially smaller, 0.100 inch for example, tends tocause the liquid to completely bridge across the passage because of theliquids surface tension and prevents air from working back up the tubeat approximately atmospheric pressure while liquid is flowing down thetube. This same phenomenon happens with a small drinking straw. If thestraw is filled with liquid and one places their finger over the top ofthe straw, the liquid will not drain from the straw. In applicantsoutlet tubes, the bores are sufiiciently large so liquid can flowdownwardly and air flow upwardly at the same time to deliver liquid tothe air trap chamber. When only one outlet tube clamp is open, liquidwill flow into the air trap chamber to replace air moving back up to thebottle. Thus, no substantial vacuum is created in the air trap chamberpreventing additional air from returning to the bottle. I have foundthat a single outlet tube with a .281 inch diameter passage, forexample, can deliver liquid to the air trap chamber very quickly at flowrates up to 950 ml per minute at approximately atmospheric pressure.

The pressure here is described as approximately atmospheric, even thoughthe pressure will sometimes be slightly higher than atmospheric as anair slug begins its journey up the outlet tube while liquid drains bygravity down the outlet tube. Because of the problems mentionedpreviously with high pressure delivery of liquid to the surgical site,it is the applicant's intent to administer liquid with his apparatus atlow gravity feed pressure to the air trap chamber rather than with highpressure pumping mechanisms. This is because such high pressure could betransmitted down the drain tube 35 to the resectoscope and causesplattering and excessive pressure build up in the patients bladder.During the gravity feed of liquid in applicants apparatus, the pressurein the air trap chamber is preferably between to percent of theatmospheric room pressure outside the liquid supply apparatus.

The air in the air trap chamber 25 in FIG. 2 shown working its way backup the outlet tube 13 could have come from several sources. It couldhave come from tiny bubbles entrained in the liquid coming down theoutlet tube, perhaps caused by shaking of the supply bottle. The bubblesmight not have had time to separate from the liquid until they were inthe air trap chamber. Air in the air trap chamber could have come fromthe air filled outlet tube 13 that was connected to a full liquid supplybottle. Liquid initially gushing down the outlet tube could have movedsome of the air in the tube down into the air trap chamber. Regardlessof where the air came from, it is important to get it out of the airtrap chamber.

As explained above, the outlet tubes have passages large enough so theair can work its way back up to the supply bottle. It does require sometime for air to work its way back to the bottles, and occasionally it isdesired to get the air out of the air trap chamber quicker than the airremoval shown in FIG. 2. This might occur when three or more bottleswere started running with air filled tubes, and a large volume of airfrom the outlet tubes was moved into the air trap chamber. To speed upthe air removal from the air trap chamber, 1 have provided a uniquecheck valve 42 shown in FIGS. 3 and 4 to assist the outlet tubes inremoving air from the air trap chamber.

The check valve shown as replacing one of the inlet tubes at an airopening in top cap 30 of the air trap chamber operates differently thanmost check valves which merely permit fluid to flow in one direction butnot the other. The check valve of this invention is comprised of twocomponents. First there is a hydrophobic filter 43 fitting within agroove of a hollow holder 44 which is wedged into the inlet port of topcap 30. The hydrophobic filter which may be a Teflon (duPont trademark-for fluroplastic) coated fabric or a microporous Teflon film which willallow air to pass through it but will not pass liquid. The secondelement of the check valve is a duck bill rubber flap valve 45 with aslit opening 46 that opens to outward air flow but closes to inward airflow. The flap valve fits over the upper end of the holder 44. The twoelements of the check valve allow air but not liquid to leave the airtrap chamber. Neither air nor liquid can enter the air trap chamberthrough the check valve. If desired, an air breathing protector cap canbe fitted over the rubber flap valve to protect it from contamination.

Should the liquid level rise to the hydrophobic filter level as shown inFIG. 3, the air trap chamber will continue to operate, because liquid inthe air trap chamber cannot move through the check valve 42. Thus, thecheck valve not only controls direction of flow, but separates air fromliquid as air exits the air trap chamber. Even when the air trap chamberis as full of liquid as in FIG. 3, the apparatus works very well. Thisis because the surgical irrigation apparatus has liquid gushing into theair trap chamber and does not depend on drop by drop transfer across along air pocket to measure flow rate as in parenteral administrationinto a patients vein.

Either with the check valve of FIGS. 3 and 4 or without the check valveas in FIGS. 1 and 2, the apparatus will continue to deliver liquid atlow pressure and fast flow rate to the resectoscope from the air trapchamber. The liquid flows out of the drain port 33 of the air trapchamber and through a drain tube 35 which has a longitudinal passagethat is approximately the same size as each of the outlet tubes leadingfrom the bottles. The liquid can freely run into the drain tube withoutbubbles or air slugs. At a lower end of the drain tube is a rigidadapter 36 with a passage of reduced size which leads to a resectoscopepassage which is also reduced in size from the drain tube passage.Because the drain tube passage is substantially larger than the adapterand resectoscope passages, the liquid can flow to the location ofadapter and resectoscope under low pressure. The physician can controlthe liquid flow to the resectoscope with on-off pinch clamp 47 which iswithin easy reach during the prostate surgery.

Another very important feature of the invention is the low pressuredelivery of liquid caused by the closure systems at the mouths of thebottles. As shown in FIG. 2, each bottle has a closure plug 48 insertedinto its mouth. The plug has a central tubular portion 49 with ribs 50that wedge against an inner surface of the bottle neck and has anexternal flange 51 that fits against a lip of the bottle mouth. Atubular holder 52, with a groove and a hydrophobic filter 53 held in thegroove, is wedgingly held within an air inlet port of the plug closure.The outlet tube has a rigid adapter 54 that is wedged into a liquidoutlet port of the closure. With this arrangement, the hydrophobicfilter in the air inlet port lets air bubble into the bottle at thelowest point of a mouth downward bottle. This air replaces the liquidthat drains out of the bottle. While the liquid-air interchange systemsare very important in getting the air out of the air trap chamber, theair from the air trap chamber is not sufficient to replace the severalliters of liquid dispensed. Most of the several liters of air enters thesupply bottles through hydrophobic filters such as 53. The hydrophobicfilter can be of the same material described above for the hydrophobicfilter in the air trap chamber check valve.

In working in the laboratory with this surgical irrigation system, Ifound that a very unusual thing happened with the closure system asshown in FIG. 2. Regardless of the height of liquid in the bottle, thehydrostatic head is established at approximately the level of the airinletting hydrostatic filter 53 of FIG. 2. This was unexpected because aclosure system with an air tube extending up through the liquidestablishes the hydrostatic head at the upper surface level of liquid inthe bottle. With an air tube system, the hydrostatic pressure isconstantly changing (decreasing) as the liquid level lowers when thebottle is draining. On the other hand, the bottle closure of FIG. 2,which has no air tube, maintains a constant hydrostatic head at thefilter, whether the bottle is full, one-half full, or nearly empty. Thishas a decided advantage in surgical irrigation because the pressure doesnot diminish as the bottles drain.

I had always expected the hydrostatic head of the liquid bottle to be atthe liquid surface of the FIG. 2 bottle until one day in the laboratoryI flexed the outlet tube of one bottle to form a U-shape that performedas a pressure manometer. To my surprise, the head was at the hydrophobicfilter and not at the upper liquid surface. Further laboratory testsverified that the hydrostatic head was at the hydrophobic filter.

The closure system that has the hydrophobic filter shown in the drawingsworks very well with either rigid glass bottles as shown in FIGS, 1 and2 or with semirigid blow molded thermoplastic bottles shown in FIG. 5.The thermoplastic bottles 55 and 56 themselves, with their indentedwaists, are the subject of another application, Ser. No. 767,356, nowU.S. Pat. No. 3,537,598, invented by Elmer F. St. Amand and assigned tothe assignee of the present application. I have discovered that whensuch blow molded semirigid thermoplastic bottles are used in combinationwith the surgical irrigation apparatus of this invention, thecombination has a unique way of assisting in moving air from the airtrap chamber back into the bot tles to replace liquid drained from thebottles. Unlike rigid glass bottles, the semirigid thermoplastic bottlesof FIG. 5 have walls 57, 58, 59 and 60 that flex inwardly slightly whenliquid begins draining from the bottle. This is because a slight vacuumis created inside the bottle caused by an initial pressure drop acrossthe air inletting filter at the mouth of the bottle when liquid isflowing very fast down the outlet tube to quickly supply an air filledoutlet tube with liquid. As the walls flex inwardly, they store energyand thereafter, they move outwardly toward their normal position andthis helps suck air back into the bottle from the air trap chamber. InFIG. 5, the bottle 56 on the right is full and has just been connectedto the right outlet tube 68 and is moving air in the empty outlet tube68 down into the air trap chamber 69. The bottle 55, on the left, haswalls that are moving outwardly slightly to help suck air from the airtrap chamber back into the left bottle through outlet tube 67. Becausethe bottle walls flex and spring back in response to pressuredifferences, the liquid levels of the two containers can oscillateslightly to equalize the pressure in the two bottles to maintainapproximately the same flow rate from each bottle to the air trapchamber. In FIG. 5, the drain tube, clamp 47, adapter 36, elastic sleeve37 are the same as in FIG. 1.

With the surgical irrigation apparatus of this invention, variousnumbers of either the glass or blow molded plastic bottles can be used.An example of the apparatus is shown with four outlet tubes connected toglass bottles in FIG. 1 and another example with two outlet tubesconnected to thermoplastic bottles is shown in FIG. 5. The surgicalirrigation apparatus will always have a plurality of outlet tubes asshown, but these could be 2, 3, 4 or more to insure an adequate liquidsupply to the air trap chamber by at least one bottle while otherbottles of the apparatus that become empty are exchanged for fullbottles.

FIG. 6 shows surgical irrigation apparatus with 4 outlet tubes assupplied to the hospital in sterile condition ready to be connected toliquid supply bottles and a resectoscope. The package in which theapparatus is sent to the hospital is conventional and is therefore notshown. The apparatus shown in FIG. 6 l have found works very well whenmade of the following materials; outlet tubes and drain tube of flexiblepolyvinyl chloride (PVC); cylindrical wall of the housing of transparentcellulose acetate butyrate thermoplastic; end caps of the air trapchamber and adapters of acrylonitrile-butadiene-styrene (ABS), theelastomeric tube of rubber or a highly plasticized polyvinyl chloridethermoplastic which exhibits elastic properties; and the protectors forthe bottle closures and elastic sleeve protector of a suitablethermoplastic.

METHOD OF USE When the physician was a prostate surgery scheduled forthe hospital operating room, the nurse prepares the patient and removesthe apparatus of FIG. 6 from its sterilized package. It is noted thatthe outlet tubes each have a closure for fitting to a bottle mouth andthese closures are supplied with the apparatus. Each closure has aprotector cap designated as 61, 62, 63 and 64 over a plug portion of theclosure to maintain it in sterile condition until ready for use. Thenurse then opens the mouths of two bottles of sterile liquid, such asdistilled water, normal saline, etc., and pulls 05 two protector capsfrom the closures. Next, these closures are plugged into the mouths oftwo liquid filled bottles, and with the clamps on these two outlet tubesclosed, the bottles are suspended in a mouth downward position from ahanging rack above the patient. The nurse can open one of the clamps 26,27, 28 or 29 on an outlet tube connected to a bottle to start liquidrunning into the air trap chamber 25. Then the bottom clamp 47 can beopened for a short period to let liquid fill the drain tube 35 afterwhich this bottom clamp is again closed. The air formerly in the draintube is either flushed out through a loose fit between the protectorsleeve 40 and retainer skirt 39 that forms a vent system, or the air canwork its way back up to the air trap chamber 25. Then, when thephysician comes into the operating room, he can go directly into theprostate surgery without having to bleed air from the drain tube 35.

When connecting the first two liquid filled bottles to supply the airtrap chamber as explained above, it is preferred to hold the closureends of the other two outlet tubes below the air trap chamber.Therefore, the second pair of lowered outlet tubes can also act as airvents to remove air from the air trap chamber. Air can vent between theclosure and their protector caps which are either ribbed or grooved at65 and have a bump 66 to keep a slight air passage between the cap andclosure. After the first two bottles start a steady liquid supply to thetrap chamber, the third and fourth bottles are opened and connected totheir respective outlet tubes and hung on the hanging stand. Now, wehave all four 2-literbottles feeding into the air trap chamber. Sinceeach bottle has an air inlet at its lowest point in the mouth downwardposition and has no air tube, all bottles hung at the same height willhave the same hydrostatic head, which is established at the hydrophobicfilter 53.

After any one of the bottles runs dry, the nurse takes it down from thehanging stand and exchanges it for a full bottle and hangs up the newbottle. This can be done with any randomly selected bottle of theapparatus without disrupting the liquid supply of any other bottle ofthe system. Therefore, all a nurse needs to keep in mind when monitoringthe supply bottles, is to change any bottle that becomes empty. She doesnot have to be concerned with any particular sequence of changingbottles to avoid air slugs or bubbles delivered to the resectoscope asmight be the case where one bottle feeds into another bottle which thendelivers the combined liquids. If only one of the several bottles inapplicants surgical irrigation apparatus has liquid, the apparatus willoperate at the low pressure, fast flow rate desired for flushing actionin a prostate surgery.

In the above description, I have used specific examples to describe myinvention. However, persons skilled in the art will understand how tomake certain modifications to those specific examples without departingfrom the spirit and scope of the invention.

I claim:

1. A substantially free-fall, gravity-feed surgical irrigation apparatuscomprising: a plurality of liquid-containing bottles with outlet portsadapted to be randomly-selected and supported above an irrigation siteor discharged and replaced without interferring with irrigationprocedures; a flexible outlet tube for each bottle with upper ends ofthese outlet tubes connected to the respective outlet ports, each of theoutlet tubes including means defining a passage sufficiently large incross sectional area from its upper end to its lower end for permittingsubstantially simultaneous counter-current flow of liquid and air atapproximately atmospheric pressure during free-fall of liquidtherethrough during a surgical irrigation procedure: an enlarged airtrap chamber having an inlet structure at its top in direct-flowcommunication with lower ends of the outlet tubes and having an outletport at its bottom, said air trap chamber having a size and capacity andfree communication between the inlet structure and outlet portpermitting free discharge of a randomly selected filled bottle to beinverted and the entire contents to be freely discharged thereinto atthe hydrostatic head developed at the outlet port of the invertedbottle; means operatively connected to said air trap chamber and saidbottles for permitting a liquid-air interface to form in said air trapchamber asliquid is permitted to freely discharge from said said outletport while liquid and air are flowing counter-currently in said flexibleoutlet tube; and a flexible drain tube connected to the drain port andwhich includes a longitudinal passage therethrough to a lower end of thedrain tube, said drain tube having a cross sectional area for permittingfree-fall liquid to be directed at a low pressure and high volumewithout entrapped air bubbles to the irrigation site, each bottlethrough its outlet tube having means providing its own independentlyoperating liquid-air interchange system with the air trap chamber, andany bottle being operable to continue to supply liquid to the air trapchamber while any other randomly selected bottle of the apparatus thatbecomes empty is replaced by a filled bottle.

2. Surgical irrigation apparatus as set forth in claim 1, wherein theapparatus has a separate valve for opening and closing the passage ofeach outlet tube, and has a valve for opening and closing the passage ofthe drain tube.

3. Surgical irrigation apparatus as set forth in claim 1, wherein thedrain tubes passage is approximately the same size as each outlet tubepassage and has a constriction adjacent its lower end, whereby the draintube can run full of liquid to deliver large volumes of liquid at lowpressure to the irrigation site without intermittant slugs of air.

4. Surgical irrigation apparatus as set forth in claim 1, wherein thedrain tube has an elastic sleeve at its lower end adapted to stretchover and grip a medical instrument.

5. Surgical irrigation apparatus as set forth in claim 1, wherein thebottles are of rigid glass.

6. Surgical irrigation apparatus as set forth in claim 1, wherein eachbottle has semirigid thermoplastic walls capable of storing energy bytemporarily bending inwardly as liquid drains from the bottle andthereafter springing outwardly to suck air back into the bottle.

7. Surgical irrigation apparatus as set forth in claim 1, wherein eachbottle has a mouth, and the apparatus includes a removable closurefitting across this mouth and having first and second ports through theclosure; the upper end of the bottles flexible outlet tube being securedto the closure at its first port; and means secured to the closure atthe second port for admitting air into the bottle and preventing liquidexit from the bottle through the second port when the bottle issuspended in a mouth downward position.

8. Surgical irrigation apparatus as set forth in claim 7, wherein themeans for admitting air is a hydrophobic filter which establishes ahydrostatic head at approximately the level of the filter so thehydrostatic head is generally constant regardless of the liquid level inthe bottle.

9. Surgical irrigation apparatus comprising: a plurality ofliquid-containing bottles with outlet ports adapted to be supportedabove an irrigation site; a flexible outlet tube for each bottle withupper ends of these outlet tubes connected to the outlet ports, each ofthe outlet tubes defining a passage sufficiently large in crosssectional area from its upper end to its lower end for simultaneousconcurrent flow of liquid and air at approximately atmospheric pressure;an enlarged air trap chamber having an inlet structure at its top inflow communication with lower ends of the outlet tubes and having anoutlet port at its bottom; and a flexible drain tube connected to thisdrain port and which includes a longitudinal passage therethrough to alower end of the drain tube for directing liquid to the irrigation site,whereby each bottle through its outlet tube has its own independentlyoperating liquid-air interchange system with the air trap chamber, andany bottle can continue to supply liquid to the air trap chamber whileany other randomly selected bottle of the apparatus that becomes emptyis replaced by a filled bottle, the apparatus having an air opening tothe atmosphere in the air trap chamber adjacent its top for assisting inair removal from the air trap chamber, and a check valve closing off theair opening, said check valve permits air but not liquid to flowoutwardly through the air opening and prevents both air and liquid fromflow into the air trap chamber through the air opening.

10. Surgical irrigationapparatus as set forth in claim 1, wherein theair trap chamber has a top cap with a separate inlet port connected toeach outlet tube.

11. Surgical irrigation apparatus as set forth in claim 1, wherein theair trap chamber has a transparent cylindrical wall that isvolumetrically calibrated.

12. Surgical irrigation apparatus as set forth in claim 1, wherein eachoutlet tube has a passage with a diameter between 0.150 and 0.400 inch.

13. Surgical irrigation apparatus as set forth in claim 1, wherein theair trap chamber has an internal pressure that is between 90 and 120percent of the atmospheric pressure outside the air trap chamber whenliquid is being supplied to the air trap chamber.

14. In surgical irrigation apparatus including a plurality of liquidcontainers each with an outlet connected to a downwardly extendingflexible tube that has a lower end, the improvement of: an enlarged airtrap chamber with an inlet structure in flow communication with thelower ends of the outlet tubes, the air trap chamber having an airopening to the atmosphere adjacent a top of the chamber and has a drainport adjacent its bottom; and a check valve secured across the airopening, which check valve permits air but not liquid to flow outwardlythrough the air opening, while preventing both air and liquid fromflowing inwardly through the air opening.

15. The improvement in surgical irrigation apparatus as set forth inclaim 14, wherein the check valve comprises the combination of a flapvalve with inner and outer ends, and a hydrophobic filter connected withthe inner end of the flap valve.

16. An assembly for use in surgical irrigation apparatus-including aplurality of liquid-containing bottles having mouths, which assemblyincludes: a plurality of closures with portions for connecting with thebottle mouths, said closures including a liquid outlet port through theclosure; removable sterility protectors fitting over said portions ofthe closures; a flexible outlet tube connected at its upper end to theoutlet port of each closure, each of the outlet tubes including meansdefining a passage sufficiently large in cross-sectional area from itsupper end to its lower end for simultaneous counter-current flow ofliquid and air at approximately atmospheric pressure during freegravity-flow of liq uid therethrough; an enlarged air trap chamberhaving an inlet structure at its top in direct-flow communication withthe lower ends of the outlet tubs and having a drain port at its bottom,said air trap chamber having a size and capacity and free communicationbetween the inlet structure and outlet port for permitting freedischarge of a randomly selected filled bottle to be inverted and theen-contents to be freely discharged therein at the hydrostatic headdeveloped at the outlet port of the bottles to which said closures havebeen attached; means operatively connected to said closures and said airtrap chamber for permitting a liquid air interface to form in said airtrap chamber as liquid is permitted to freely discharge from said outletport while liquid and air are flowing counter-courently in said flexibleoutlet tube; a flexible drain tube connected to this drain port andhaving a passage of sufficient capacity for permitting liquid to freelyfall therethrough at low pressure and high volume without entrapped airbubbles for directing liquid from its lower end to an irrigation site;and a removable protector housing fitted over a lower end of the draintube, each outlet tube is adapted to provide an independent air-liquidinterchange system between a bottle and the air trap chamber.

17. Surgical irrigation apparatus comprising: a plurality ofliquid-containing bottles, each with a mouth and adapted to be suspendedin a mouth-downward position above an irrigation site with the liquidfreely flowing therefrom under the force of gravity; a removable closurefitting across the mouth of each bottle and having first and secondports therethrough; through; a flexible outlet tube with an upper endconnected to the first port of each respective closure, each outlet tubeincluding means having a lower end and a passage between its endssufficiently large in cross-sectional area for simultaneouscounter-current flow of liquid and air at approximately atmosphericpressure; a pinch clamp on each outlet tube for opening and closing itspassage; a hydrophobic filter fitting across the second port of theclosure to admit air into the bottle and to prevent liquid exit from thebottle through the second port when the bottle is suspended in a mouthdownward position, said bottles developing a hydrostatic head facetherein when liquid in permitted to freely drain from theair trapchamber, each bottle through its tube forming an independent liquid-airinterchange system with the air trap chamber, and any randomly-selectedbottle and its system continuing to function after any other bottle ofthe apparatus becomes empty and is replaced by a filled bottle; aflexible drain tube connected at its upper end to the drain port of theair trap chambers bottom cap, and having a passage between its upper andlower ends that is approximately the same size as each outlet tubepassage for permitting liquid to freely flow therethrough at a lowpressure and high volume without entrapped bubbles; and adaptor with aconstricted opening connected to the drain tubes lower end, said adapterhaving a cross section so the drain tube can run full of liquid todeliver large volumes of liquid at low pressure to the irrigation sitewithout intermittant slugs of air; an elastic sleeve secured to theadapter for stretching over and gripping to a medical instrument; and aremovable protector housing fitting over the elastic sleeve.

18. A method of surgical irrigation for continuously supplying asubstantially air-free liquid to an irrigation site when effecting aTransurethral Resection or similar surgical procedure at a low pressureand large volume, comprising the steps of:

A. filling a plurality of containers with an irrigation liquid;

B. independently connecting each of the filled bottles to an an enlargedair chamber through independent outlet tubes and permitting air andliquid flowing therethrough to have counter-current flow therethrough asa filled bottle is emptied into air chamber;

C. connecting the air trap chamber to a drain tube for permitting liquidto drain therethrough at a low pressure and high volume withoutentrapped air bubbles therein;

D. randomly selecting two or more of the filled bottles,

suspending the same in a discharge attitude above an irrigation site;

E. emptying one of the suspended bottles into the air trap chamber whilestarting to empty another of the suspended bottles into the chamberbefore the first is completely empty so that liquid for irrigation isuninterrupted;

F. continuing to discharge liquid into the air trap chamber at ahydrostatic head developed at the bottle being discharged whilereplacing the emptied bottle with one that is filled; and

G. effecting the discharge of liquid through the air trap chamber whilemaintaining an air liquid interface in said air trap chamber during freegravity flow of liquid therethrough.

19. A method of surgical irrigation as set forth in claim 18 whereinthere are four liquid containing bottles and four outlet tubes leadingbetween the bottles and the air trap chamber, and the method includesthe step of completely emptying any two randomly selected bottles andthen disconnecting and replacing them with filled bottles while liquidis supplied to the air trap chamber by at least one of the other twobottles.

1. A substantially free-fall, gravity-feed surgical irrigation apparatuscomprising: a plurality of liquid-containing bottles with outlet portsadapted to be randomly-selected and supported above an irrigation siteor discharged and replaced without interferring with irrigationprocedures; a flexible outlet tube for each bottle with upper ends ofthese outlet tubes connected to the respective outlet ports, each of theoutlet tubes including means defining a passage sufficiently large incross sectional area from its upper end to its lower end for permittingsubstantially simultaneous counter-current flow of liquid and air atapproximately atmospheric pressure during free-fall of liquidtherethrough during a surgical irrigation procedure: an enlarged airtrap chamber having an inlet structure at its top in directflowcommunication with lower ends of the outlet tubes and having an outletport at its bottom, said air trap chamber having a size and capacity andfree communication between the inlet structure and outlet portpermitting free discharge of a randomly selected filled bottle to beinverted and the entire contents to be freely discharged thereinto atthe hydrostatic head developed at the outlet port of the invertedbottle; means operatively connected to said air trap chamber and saidbottles for permitting a liquid-air interface to form in said air trapchamber as liquid is permitted to freely discharge from said said outletport while liquid and air are flowing counter-currently in said flexibleoutlet tube; and a flexible drain tube connected to the drain port andwhich includes a longitudinal passage therethrough to a lower end of thedrain tube, said drain tube having a cross sectional area for permittingfree-fall liquid to be directed at a low pressure and high volumewithout entrapped air bubbles to the irrigation site, each bottlethrough its outlet tube having means providing its own independentlyoperating liquid-air interchange system with the air trap chamber, andany bottle being operable to Continue to supply liquid to the air trapchamber while any other randomly selected bottle of the apparatus thatbecomes empty is replaced by a filled bottle.
 2. Surgical irrigationapparatus as set forth in claim 1, wherein the apparatus has a separatevalve for opening and closing the passage of each outlet tube, and has avalve for opening and closing the passage of the drain tube.
 3. Surgicalirrigation apparatus as set forth in claim 1, wherein the drain tube''spassage is approximately the same size as each outlet tube passage andhas a constriction adjacent its lower end, whereby the drain tube canrun full of liquid to deliver large volumes of liquid at low pressure tothe irrigation site without intermittant slugs of air.
 4. Surgicalirrigation apparatus as set forth in claim 1, wherein the drain tube hasan elastic sleeve at its lower end adapted to stretch over and grip amedical instrument.
 5. Surgical irrigation apparatus as set forth inclaim 1, wherein the bottles are of rigid glass.
 6. Surgical irrigationapparatus as set forth in claim 1, wherein each bottle has semirigidthermoplastic walls capable of storing energy by temporarily bendinginwardly as liquid drains from the bottle and thereafter springingoutwardly to suck air back into the bottle.
 7. Surgical irrigationapparatus as set forth in claim 1, wherein each bottle has a mouth, andthe apparatus includes a removable closure fitting across this mouth andhaving first and second ports through the closure; the upper end of thebottle''s flexible outlet tube being secured to the closure at its firstport; and means secured to the closure at the second port for admittingair into the bottle and preventing liquid exit from the bottle throughthe second port when the bottle is suspended in a mouth downwardposition.
 8. Surgical irrigation apparatus as set forth in claim 7,wherein the means for admitting air is a hydrophobic filter whichestablishes a hydrostatic head at approximately the level of the filterso the hydrostatic head is generally constant regardless of the liquidlevel in the bottle.
 9. Surgical irrigation apparatus comprising: aplurality of liquid-containing bottles with outlet ports adapted to besupported above an irrigation site; a flexible outlet tube for eachbottle with upper ends of these outlet tubes connected to the outletports, each of the outlet tubes defining a passage sufficiently large incross sectional area from its upper end to its lower end forsimultaneous concurrent flow of liquid and air at approximatelyatmospheric pressure; an enlarged air trap chamber having an inletstructure at its top in flow communication with lower ends of the outlettubes and having an outlet port at its bottom; and a flexible drain tubeconnected to this drain port and which includes a longitudinal passagetherethrough to a lower end of the drain tube for directing liquid tothe irrigation site, whereby each bottle through its outlet tube has itsown independently operating liquid-air interchange system with the airtrap chamber, and any bottle can continue to supply liquid to the airtrap chamber while any other randomly selected bottle of the apparatusthat becomes empty is replaced by a filled bottle, the apparatus havingan air opening to the atmosphere in the air trap chamber adjacent itstop for assisting in air removal from the air trap chamber, and a checkvalve closing off the air opening, said check valve permits air but notliquid to flow outwardly through the air opening and prevents both airand liquid from flow into the air trap chamber through the air opening.10. Surgical irrigation apparatus as set forth in claim 1, wherein theair trap chamber has a top cap with a separate inlet port connected toeach outlet tube.
 11. Surgical irrigation apparatus as set forth inclaim 1, wherein the air trap chamber has a transparent cylindrical wallthat is volumetrically calibrated.
 12. Surgical irrigation apparatus asset forth in claim 1, wherein each outleT tube has a passage with adiameter between 0.150 and 0.400 inch.
 13. Surgical irrigation apparatusas set forth in claim 1, wherein the air trap chamber has an internalpressure that is between 90 and 120 percent of the atmospheric pressureoutside the air trap chamber when liquid is being supplied to the airtrap chamber.
 14. In surgical irrigation apparatus including a pluralityof liquid containers each with an outlet connected to a downwardlyextending flexible tube that has a lower end, the improvement of: anenlarged air trap chamber with an inlet structure in flow communicationwith the lower ends of the outlet tubes, the air trap chamber having anair opening to the atmosphere adjacent a top of the chamber and has adrain port adjacent its bottom; and a check valve secured across the airopening, which check valve permits air but not liquid to flow outwardlythrough the air opening, while preventing both air and liquid fromflowing inwardly through the air opening.
 15. The improvement insurgical irrigation apparatus as set forth in claim 14, wherein thecheck valve comprises the combination of a flap valve with inner andouter ends, and a hydrophobic filter connected with the inner end of theflap valve.
 16. An assembly for use in surgical irrigation apparatusincluding a plurality of liquid-containing bottles having mouths, whichassembly includes: a plurality of closures with portions for connectingwith the bottle mouths, said closures including a liquid outlet portthrough the closure; removable sterility protectors fitting over saidportions of the closures; a flexible outlet tube connected at its upperend to the outlet port of each closure, each of the outlet tubesincluding means defining a passage sufficiently large in cross-sectionalarea from its upper end to its lower end for simultaneouscounter-current flow of liquid and air at approximately atmosphericpressure during free gravity-flow of liquid therethrough; an enlargedair trap chamber having an inlet structure at its top in direct-flowcommunication with the lower ends of the outlet tubs and having a drainport at its bottom, said air trap chamber having a size and capacity andfree communication between the inlet structure and outlet port forpermitting free discharge of a randomly selected filled bottle to beinverted and the en-contents to be freely discharged therein at thehydrostatic head developed at the outlet port of the bottles to whichsaid closures have been attached; means operatively connected to saidclosures and said air trap chamber for permitting a liquid air interfaceto form in said air trap chamber as liquid is permitted to freelydischarge from said outlet port while liquid and air are flowingcounter-courently in said flexible outlet tube; a flexible drain tubeconnected to this drain port and having a passage of sufficient capacityfor permitting liquid to freely fall therethrough at low pressure andhigh volume without entrapped air bubbles for directing liquid from itslower end to an irrigation site; and a removable protector housingfitted over a lower end of the drain tube, each outlet tube is adaptedto provide an independent air-liquid interchange system between a bottleand the air trap chamber.
 17. Surgical irrigation apparatus comprising:a plurality of liquid-containing bottles, each with a mouth and adaptedto be suspended in a mouth-downward position above an irrigation sitewith the liquid freely flowing therefrom under the force of gravity; aremovable closure fitting across the mouth of each bottle and havingfirst and second ports therethrough; through; a flexible outlet tubewith an upper end connected to the first port of each respectiveclosure, each outlet tube including means having a lower end and apassage between its ends sufficiently large in cross-sectional area forsimultaneous counter-current flow of liquid and air at approximatelyatmospheric pressure; a pinch clamp on each outlet tube for opening andclosing its passaGe; a hydrophobic filter fitting across the second portof the closure to admit air into the bottle and to prevent liquid exitfrom the bottle through the second port when the bottle is suspended ina mouth downward position, said bottles developing a hydrostatic headsubstantially at said filter when liquid is permitted to freely fallfrom the bottles; an enlarged air trap chamber including a transparentcylinderical housing, an upper cap secured to a top of the housing andhaving a separate inlet port in communication in communication with eachoutlet tube''s lower end, and a lower cap secured secured to a bottom ofthe housing and having a drain port therethrough; means operativelyconnected to said air trap chamber developing a liquid-air interfacetherein when liquid in permitted to freely drain from the air trapchamber, each bottle through its tube forming an independent liquid-airinterchange system with the air trap chamber, and any randomly-selectedbottle and its system continuing to function after any other bottle ofthe apparatus becomes empty and is replaced by a filled bottle; aflexible drain tube connected at its upper end to the drain port of theair trap chamber''s bottom cap, and having a passage between its upperand lower ends that is approximately the same size as each outlet tubepassage for permitting liquid to freely flow therethrough at a lowpressure and high volume without entrapped bubbles; and adaptor with aconstricted opening connected to the drain tubes lower end, said adapterhaving a cross section so the drain tube can run full of liquid todeliver large volumes of liquid at low pressure to the irrigation sitewithout intermittant slugs of air; an elastic sleeve secured to theadapter for stretching over and gripping to a medical instrument; and aremovable protector housing fitting over the elastic sleeve.
 18. Amethod of surgical irrigation for continuously supplying a substantiallyair-free liquid to an irrigation site when effecting a ''''TransurethralResection'''' or similar surgical procedure at a low pressure and largevolume, comprising the steps of: A. filling a plurality of containerswith an irrigation liquid; B. independently connecting each of thefilled bottles to an an enlarged air chamber through independent outlettubes and permitting air and liquid flowing therethrough to havecounter-current flow therethrough as a filled bottle is emptied into airchamber; C. connecting the air trap chamber to a drain tube forpermitting liquid to drain therethrough at a low pressure and highvolume without entrapped air bubbles therein; D. randomly selecting twoor more of the filled bottles, suspending the same in a dischargeattitude above an irrigation site; E. emptying one of the suspendedbottles into the air trap chamber while starting to empty another of thesuspended bottles into the chamber before the first is completely emptyso that liquid for irrigation is uninterrupted; F. continuing todischarge liquid into the air trap chamber at a hydrostatic headdeveloped at the bottle being discharged while replacing the emptiedbottle with one that is filled; and G. effecting the discharge of liquidthrough the air trap chamber while maintaining an air liquid interfacein said air trap chamber during free gravity flow of liquidtherethrough.
 19. A method of surgical irrigation as set forth in claim18 wherein there are four liquid containing bottles and four outlettubes leading between the bottles and the air trap chamber, and themethod includes the step of completely emptying any two randomlyselected bottles and then disconnecting and replacing them with filledbottles while liquid is supplied to the air trap chamber by at least oneof the other two bottles.